Folding umbrella



H. HAUPT FOLDING UMBRELLA Filed Oct. 26, 1938 Attorney Patented May 9, 1939 UNITED sTA'rEs PATENT OFFECE Application October 26, 1938, Serial No. %7,080 In Germany October 26, 1937 Clains.

`"5 the said locking device consists of a spring actuated latch mounted within one of the said tubular stick members and held by its spring in locking engagement with the other stick member, While under normal conditions the force of the spring is suflicient to hold the said latch in locking position against the axial pressure eXerted on the said latch by the said other stick member, it is pressed inwardly and out of locking position by an additional force exerted on the stick member by the user for collapsing the umbrella. The object of the improvements is to provide a locking device of this type in which a comparatively Weak spring is needed for holding the said latch in locking position, and in which notwith- 20 standing this the stick members are safely held in extended position. With this object in View my invention consists in constructing the locl 'ng devioe of a rigid pivotally mounted latch disposed within the stick member longitudinally "25 thereof and adapted to take up most of the axial 5 For the purpose of explaining the invention an example embodying the same has been shown in the accompanying drawing in which the same reference characters have been used in all the views to indicate corresponding parts. In said i 40 drawing,

Fig. 1 is a fragmentary sectional elevation on an enlarged scale showing the engaging ends of a pair of stock members in extended and locked position,

Fig. 2 is a similar sectional elevation showing the locking device nearly disengaged,

Fig. 3 is an elevation showing the latch of the locking device and a diagram illustrating the 50 forces exerted thereon, and

Fig. 4 is a diagram of forces. In the example shown in the figures the stick comprises two telescopic stick members a and b, v

the said stick members being shown in extended 55 position. Within the inner stick member a rigid latch d is pivotally mounted on a pivot bolt c, the said latch being preferably punched from sheet metal. In the Construction shown in the figures the said latch is directed downwardly from its pivot bolt c, and at its bottom end it is formed with a nose e having its upper edge f siightly inclined outwardly and downwardly from a trans- Verse plane. Below the latch d a curved leaf spring m is loosely mounted within the stick member a, and the said leaf spring engages the 10 wall of the member a at opposite sides at h and ic and at its top end it is formed with a longitudinal slot n engaging a nose 0` 'ormed on and projecting from the rear side of the latch d, the said slot having a length such that the nose o has free play therein in any position of the latch.

The stick members are provided with Slots p and oj through which the nose 'e is projected by the spring m into locking position, the bevelled edge f being engaged in the said position of the latch by the upper edge r of the slot q of the enter stick member b.

By the stick member b a force is exerted on the latch d which acts thereon in a direction parallel to the-longitudinal axis of the stick, and which has a Component S acting'perpendicularly to the said bevelled edge f. The said Component S is shown in Fig. 3 in dotted lines, and the axs of the stick is represented by a broken line A-A. When additional axial pressure is exerted on the stick member b the nose e is pressed inwardly and in the direction of the arrow .r shown in Fig. 3, and the said inward movement iscounteracted, not only by the spring m, but also by the riction of the edge r of the stick member b and the bevelled edge f of the latch, the said force caused by frotion being indicated in Fig. 3 by the letter R. The forces S and R are combined into a force T, which is inclined from the direction of the force S at an angle Q representing the angle of 40 friction.

In addition the latch d is acted upon by a force U exerted by the spring m, the direction of the said force intersecting the direction of the force T at O. The forces T and U are held in equlibi 5 rinin by a force V passing through the point O and intersecting the pivot bolt c. With a given force T the force U of the spring needed for holding the latch in equilibrium may be ascertained from the polygon of forces shown in Fig. 4. This polygon shows that the force U is Smail as compared to the force T, and that therefore only a Weak spring is needed. But the force V which istransmitted through 'the latch d to the pivot 5 bolt c is large, and therefore, it is important that the said latch is rigid, so that it is able to take up the force without objectionable deformation.

Fig. 4 also shows that the size of the force U depends on the position of the pivot bolt relatively to the point r and therefore on the inclination of the said latch relatively to the axis of the stick, and therefore the necessary force of the spring may be reduced as far as desired by suitably selecting the said inclination of the latch d or the position of the pivot bolt c. The necessary strength of the spring is at its minimum if the said latch is nearly parallel to the axis of the stick, and the pivot bolt is near the left hand side wall of the stick. But it is not advisable to place the pivot bolt c quite near the said side wall, because then the direction of the force T which depends on the inclination of the edge f has a greater influence on the size of the spring force U, so that a change of the form of the said edge caused by the wear thereof might have the result that the spring is not sufficient any more for holding the latch d in looking position against the normal axial pressure of the stick member b thereon, or vice versa, that the stick can be collapsed only by high force.

Figs. 3 and 4 also show that a considerable part of the supporting force of the edge f is supplied by the iriction of rest at r, as will be understood if in the diagram shown in Fig. 4 in lieu of the force T the force S were shown which does not include the said iriction, in which case the force U would be much larger. Thus, the possibility of providing a Weak spring is based on two causes.

Fig. 2 shows how the nose e recedes shortly after the beginning of the inward movement of the stick members. By reason of the rigidity of the latch d it is impossible that the nose e is bent rearwardly on the latch d immediately after the friction has been overcome, as would be the case if in lieu of the rigid latch d and the spring m acting thereon a spring latch d were provided. In my improved construction the upper edge r of the slot q slides on the edge ,f during a larger part of the inward movement of the stick members, and the friction produced by such movement prevents a sudden reduction of the supporting power of the latch to zero. Therefore the stick members are gradually and smoothly collapsed, which is important because a sudden and unexpected collapsing of the said members would endanger the cover of the umbrella.

As viewed from its point of suspension, that is the pivot bolt c, the latch d is located in the direction of the inward movement of the stick member b and therefore the inclination of the edge f from the horizontal plane increases as the nose e recedes inwardly, and accordingly the frictional resistance is gradually reduced. The leaf spring m is located within the stick member a below the latch d and at a part where there is sufficient room. Therefore the leaf spring may have any desired length, so that the force exerted thereby is not materially increased when the latch d is pushed inwardly. During this movement the parts d and m are moved longitudinally of the stick in opposite directions, and therefore, if the spring were connected with the latch so as to be non-shiftable relatively thereto, the spring would be axially compressed and deformed. Such deformation is prevented by the loose connection between the nose o and the leaf spring m.

While in describing the invention reference has been made to a particular example embodying the same I wish it to be understood that my invention is not limited to the construction shown in the figures, and that various changes may be made in the general construction of the device and the arrangement of its parts without departing from the invention. For example, in lieu of a one-armed latch d a two-armed latch may be provided, in which the spring, such for example as a coiled spring, engages the free arm of the latch d which may be located for example transversely of the stick. But I prefer the construction shown in the figures because the parts are in a better way adapted to the narrow space within the stick member a.

As is known to those skilled in the art, it is important in umbrellas of the type indicated that the force exerted by the spring on the latch be small, in View of the wear of the inner wall of the stick by the spring pressed latch sliding thereon. In my improved construction the said force of the spring is small, because only a comparatively small Component of the pressure of the upper stick member on the said latch counteracts the said spring, and because at the beginning of the collapsing movement of the stick members the latch is pressed inwardly and the relative movement between the edges f and r is counteracted by the friction between the said edges. Further, the axial pressure of the stick member b is taken up by the rigid latch d, and it is not taken up by the spring m, and therefore it is not necessary to strengthen the said spring so that it is able to take up the said axial pressure without being deformed thereby. My improved construction is valuable also for the reason that the nose e of the latch cannot be bent inwardly by deformation of the latch, which would result in a sudden reduction of the friction to zero and a sudden collapsing of the stick. such sudden collapsing of the stick might injure the cover.

I am aware that heretofore spring latches have been provided in which a pivotally mounted rigid two-armed latch is located transversely within the stick and acted upon by a coiled spring acting on the free arm of the latch. As distinguished ironi this structure, in my improved looking device the spring must take up only a small component of the axial force exerted on the latch by the telescopic stick members, and therefore a Weak spring is suicient. Further, I am aware that a looking device for telescopic stick members has been provided which comprises a pivotally mounted rigid latch acted upon by a leaf spring, the said latch being formed with a nose having a looking edge disposed perpendicularly to the direction of the movement of the stick members, a separate member being provided for retracting the latch out of looking position. As distinguished from this construction in my umbrella the leaf spring provides an element necessary for holding the spring latch in looking engagement with the outer stick member, and the looking edge of the latch is disposed angularly of the direction of the movement of the outer stick member and so that the latch is pressed inwardly against the pressure of the spring by the axial force exerted on the outer stick member.

As is shown in Fig. 1, the edge f is inclined outwardly and away from the line connecting the pivot c and the point of engagement of the edge f with the point r.

I claim:

1. In a foldlng umbrella, a stick comprising a pair of telescoping members, a rigid latch pivotally mounted within one of said members and disposed longitudinally thereof and having a nose adapted With one edge for looking engagement with the other member, said edge being bevelled outwardly and away from a line oonnecting the point of engagement of said edge and the pivot of said iatch, and a spring acting on said latch and tending to hold the same in looking position, the bevel of said looking edge and the force eX- erted by said spring on said latch being such that under normal longitudinal pressure exerted on said nose by said members the nose is held in looking position and that by additional longitudinal pressure exerted thereon the latch is pressed out of looking position.

2. An umbrella stick as claimed in claim 1, in which the said latch extends from its pivot in the direction of the inward movement of the stick member to be supported thereby.

3. An umbrella stick as claimed in claim 1, in which the said rigid latch and its nose are made in one piece.

4. An umbrella stick as claimed in claim 1, in which the said spring is located within the stick member at the side of the latch remote from the pivotai axis thereof.

5. An umbrella stick as claimed in claim 1, in which the spring is located within the stick member at the side of the latch remote from the pivotal axis thereof, the said spring engaging the latch With longitudinal play.

HANS HAUPT. 

